1. Technical Field
The present invention pertains to improvements in methods and apparatus for thermally treating surgically sterile liquid, and in using these types of systems, typically located in a surgical operating room, to thermally treat objects (e.g., sponges, needles, scalpels, endoscopes, containers, etc.) in a sterile manner. In particular, the present invention is an improvement of the methods and apparatus disclosed in U.S. Pat. No. 4,393,659 (Keyes et al.), U.S. Pat. No. 4,934,152 (Templeton), U.S. Pat. No. 5,333,326 (Faries, Jr. et al.), U.S. Pat. No. 5,522,095 (Faries, Jr. et al.), U.S. Pat. No. 6,087,636 (Faries, Jr. et al.) and U.S. Pat. No. 6,810,881 (Faries, Jr. et al.), the disclosures of which are incorporated herein by reference in their entireties.
2. Discussion of Related Art
The Keyes et al. patent discloses a surgical slush producing system having a cabinet with a heat transfer basin at its top surface. A refrigeration mechanism in the cabinet takes the form of a closed refrigeration loop including: an evaporator in heat exchange relation to the exterior of the heat transfer basin; a compressor; a condenser; and a refrigeration expansion control, all located within the cabinet. A separate product basin is configured to be removably received in the heat transfer basin. Spacers, in the form of short cylindrical stubs or buttons are arranged in three groups spaced about the heat transfer basin and projecting into the heat transfer basin interior to maintain a prescribed space between the two basins. During use, that space contains a thermal transfer liquid, such as alcohol or glycol, serving as a thermal transfer medium between the two basins. A sterile sheet of material, impervious to the thermal transfer medium, is disposed between the product basin exterior and the liquid thermal transfer medium to preserve the sterile nature of the product basin. Surgically sterile liquid, such as sodium chloride solution, is placed in the product basin and congeals on the side of that basin when the refrigeration unit is activated. A scraping tool is utilized to remove congealed sterile material from the product basin side to thereby form a slush of desired consistency in the product basin.
As noted in the Templeton patent, the above-described system has a number of disadvantages. In particular, the separate product basin must be removed and resterilized after each use. Additionally, the glycol or other thermal transfer medium is typically highly flammable or toxic and, in any event, complicates the procedure. The Templeton patent discloses a solution to these problems by constructing an entirely new apparatus whereby the product basin is eliminated in favor of a sterilized drape impervious to the sterile surgical liquid, the drape being made to conform to the basin and directly receive the sterile liquid. Congealed liquid is scraped off the sides of the conformed drape receptacle to form the desired slush.
In addition, the Templeton patent discloses an electrical heater disposed at the bottom of the basin to convert the sterile slush to warmed liquid, or heat additional sterile liquid added to the basin. The Templeton patent describes the need for such warm sterile liquid as occurring after a surgical procedure is completed to facilitate raising the body cavity of a surgery patient back to its normal temperature by contact with the warm liquid. However, there are a number of instances during a surgical procedure when it is desirable to have simultaneous access to both the sterile warm liquid and the sterile surgical slush. For example, if the surgical slush is not of the desired consistency (e.g., too thick), the availability of warm sterile liquid to be added to the slush permits rapid adjustability of the slush consistency. Likewise, maintaining instruments at or near body temperature during surgery is a desirable feature permitted by warm sterile liquid. Of course, if the warm sterile liquid is simultaneously available with the surgical slush, there is no need to wait for the slush to melt at the end of the surgical procedure. Finally, the simultaneous provision of slush and warm liquid permits the two to be comprised of different compounds as is sometimes necessary for various surgical procedures.
In response to the foregoing problems, the Faries, Jr. et al. patent (U.S. Pat. No. 5,333,326) provides a thermal treatment system having a basin for containing warm surgical liquid placed adjacent a surgical slush basin of the type, for example, disclosed in the Templeton patent. The warming basin may be a separate unit secured to the pre-existing surgical slush unit, or may be constructed as part of an integral cabinet for the warming and cooling basins. A large surgical drape covers both of the basins and contains the warm liquid and the slush in a sterile manner. Alternatively, the thermal treatment system may include only the warming basin utilizing a drape to cover the basin and contain warm surgical liquid in a sterile manner.
Thus, the warmer disclosed in the aforementioned Faries, Jr. et al. patent utilizes a basin for containing thermally treated sterile liquids (e.g., irrigation solutions, etc.). Since the basin itself is generally not sterile, and to avoid contaminating objects that are placed in the basin during a surgical procedure, a sterile surgical drape is placed in the basin to line or cover the bottom and side walls of the basin and serves as a barrier to contain the thermally treated liquid isolated from the non-sterile basin walls. A warming type basin may be a separate unit, or the basin may be constructed as part of an integral cabinet for both warming and cooling (i.e., surgical slush) basins, or the warming basin may be separate but secured to a pre-existing surgical slush unit.
Generally, users of the aforementioned Faries, Jr. et al. system utilize the liquid in the warming basin to heat objects (e.g., medical instruments, containers) placed in the basin. However, during the course of a surgical procedure, objects are often tossed, dropped or not carefully placed in the basin which sometimes causes the surgical drape or sheet to be punctured or torn, thereby compromising the required sterility. Often it is not until after the surgical procedure has been completed that it becomes evident that sterility has been compromised. Although some open basin thermal treatment systems and drapes employ a trivet or stand (e.g., U.S. Pat. No. 6,087,636) to elevate objects within the basin above the basin floor, or have been adapted to detect when the cover has been punctured and alert the surgical staff (e.g., U.S. Pat. No. 6,810,881), these systems generally do not shield or reinforce the drape to prevent puncture.